Asif can do a job in 15 hours, and Russel can do the same job in 9 hours. If they start doing the job together at 6 a.m. and Russel stops working at 9 a.m. at what time will Asif finish the job?

Correct Answer: 2p.m.
6 am to 9 am is 3 hour Asif, Needs 15 hrs to do 1 whole work 3 needs 3/9 = 1/3 work left = 1 - ( 1/5 + 1/3) = 1 - 8/15 = 7/15 Asif can do 1 work in 15 hours asif can do 7/15 work ( 15×7) /15 = 7 hour 7 hour after 9 am is 2 pm